Electron Microscopy of Pulmonary Oedema
The major mechanisms responsible for pulmonary oedema traditionally come under two headings: hydrostatic and cytotoxic. Thus oedema of the lungs may be due to hydrostatic/oncotic forces acting on vessels of normal permeability, or to cytotoxic factors which enhance permeability irrespective of pressure gradients. Tracer substances normally retained within the blood stream are thought to distinguish between these two mechanisms by escaping when cytotoxic factors increase vascular permeability. It has been demonstrated however that permeability is affected by purely hydrostatic forces, so blurring the traditional distinction between hydrostatic and cytotoxic oedema (Pietra et al., 1968; Schneeberger and Karnovsky, 1971). Nevertheless it is convenient to consider the causes of pulmonary oedema as acting under one or other of these two mechanisms.
KeywordsPulmonary Oedema Clara Cell Cytotoxic Oedema Oedema Fluid Pinocytotic Vesicle
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